Insulator.



J. E. MAIR.

INSULATOB.

APPLICATION FILED Nev. 28. 19I6.

Patented July 3, 1917.

UNITED STATES PATENT OFFICE.

JOHN E. MAIR, OF PITTSBURGH, PENNSYLVANIA, ASSIGNOR. TO THE BRUNT TILE & PORCELAIN COMPANY, OF COLUMBUS, OHIO, A CORPORATION OF OHIO.

nvsonaron.

Application filed November 28, 1916.

To all whom it may concern:

Be it known that 1, JOHN E. Mara, a citizen of the United States, residing at Pitts burgh, in the county of Allegheny and State of Pennsylvania, have invented new and useful Improvements in Insulators, of which the following is a specification.

This invention relates to improvements in insulators or wiring knobs for electrical conductors of that general type which includes a base and a cap.

The objects of the invention, briefly stated, are to provide an insulator of the type referred to which shall hold the wire or wires with the utmost security but which shall not be liable to breakage; which shall be adaptable or self-adjusting for all sizes of wires, ranging from the smallest practical to the largest permitted by the under-writers or other authorities for installation with the type of insulators referred to; which may be readily assembled and fitted to its support; and which shall be exceedingly economical to manufacture.

With the above objects in view, the inven tion consists in the novel and peculiar structure and relation of the base and the cap whereby the wire between these elements is deformed with a pronounced and extensive arcnate bend, and is, at the same time, subjected to wedging pressure whose thrusts are so directed that they will be resisted by parts of the base and the cap having thickness amply sufficientto avoid cracking or break ing under the stress imposed; and whereby wires of any diameter within the limits above stated can be fitted between and securely retained by the said base and cap.

A preferred embodiment of the invention is illustrated in the accompanying drawings, wherein Figure 1 is an elevation of the insulator with its parts in operative relation;

Fig. 2 is a vertical central sectional view showing the base and cap in detached relation;

Fig. 3 is a similar view showing the parts in operative relation and showing the wires as secured between the base and cap;

Fig. 4: is a top plan view of the base;

Fig. 5 is a top plan view, partly in section, of the insulator with its parts in operative relation.

Specification of Letters Patent.

Patented July 3, 1917'.

Serial No. 133,980.

Similar characters of reference designate corresponding parts throughout the several views.

The insulator includes a base 1, a cap and a fastening 3, 6., a screw or nail, for holding said base and cap in operative relation and for securing the insulator to its support 4, said base and cap having central openings 5 and 6, respectively, for the shank of the fastening 3.

The cap 2 has a uniformly and regularly tapered active surface 7 which is preferably conical and extends substantially to the lower end of said cap; and the base 1 has a central seat 8 for the cap which conforms to the outline of the active surface 7 but is of substantially less length, 6., extent as measured from top to bottom), than said surface whereby a substantial portion of the surface 7 6., a zone occupying approximately a third of said surface adjacent the upper end of the cap) will be above the seat 8 in the assembled relation of the part.

The seat 8 opens to the upper surface of the base 1; and said base is provided adjacent the upper edge of the seat 8 and at opposite sides thereof with wire seats 9. In the embodiment disclosed, where the cap is of conical form, the wire seats 9 are atforded by an annular shoulder 10 which circumscribes the seat 8 at the upper edge thereof and preferably extends at a slight upward angle therefrom.

The base preferably has at opposite sides of the annular shoulder 10 wire centering flanges 11 whose adjacent terminals are suitably spaced from one another to provide re cesses 12 through which the wires are led, as clearly shown in Fig. That portion of each wire which passes through the insulator is laterally bent along an arc conform-- ing to the curvature of the wire seats 9; and the extent of the lateral bend in the wire is determined by the extent of the flanges 11, since the terminals of the lateral bend of the wire adjoin the terminals of said flanges beyond which the wires extend in parallel re lation. The flanges 11 preferably each extend through a quarter of a circle; and each wire is, therefore, laterally bent through av quarter of a circle, the effect of such lateral bend being to enable the wire to be securely held with relatively light wedging pressure between the wire seats 9 and that portion of the conical surface of the cap 2 which over hangs said seats.

As will be manifest from Fig. 8, the wire seats 9, in conjunction with the confronting or overhanging portion of the conical surface of the cap 2 provide wire-receiving mouths preferably having a V-shaped crosssection and in which the deformed or laterally bent portions of the wires are wedged, the wedging thrust being perpendicular to the surfaces of the cap 2 and the wire seats 9 whereby said thrusts will be resisted by relatively thick portions of the stock of the cap and the base, respectively, above and below said wire seats, as indicated by the dotted lines A and B; and it is to be observed that the cap and the base require no special enlargement to provide these relatively thick thrust resisting portions. The flanges 11 are upright from the shoulder 10 and are provided to center the wires in the I wire seats 9 and to assist in sharply defining or setting off the relatively extensive lateral bends in the portions of the wires which are secured or gripped between the cap 2 and the seats 9; and in the exercise of these functions, the flanges 11 are not relied upon to produce any direct gripping effect on the wires and they are not subjected to any appreciable lateral pressure such as might cause their breakage.

Since the cap has a regularly tapered active surface and is supported by the wires, and may, therefore, be set at any elevation relative to the base 1, it follows that wires of any diameter within the range permis sible may be efficiently secured by the cap in cooperation with the wire seats 9 in the manner above described. Stated otherwise, the cap is self-adjusting or self-compensating for variations in the diameter of the different kinds of wire with which the insulator may be employed.

1 claim as my invention 1. An insulator comprising a base and a cap, the cap having a regularly tapered active surface extending substantially to its lower end and the base having a central seat for the cap conforming to but of substantially less depth than said surface whereby when the cap is in said seat the upper portion of its active surface is above said seat, the base also having shouldered wire seats extending from the upper edge of said-central seat and which are overhung by the said upper portion of the active surface of the cap and cooperative with said surface to provide wire-receiving mouths wherein the wires are bent laterally, said wire seats having such angle of inclination that the wires are subjected thereby and by said cap to gripping pressure whose thrusts are resisted by a relatively thick portion of the cap above said wire seats and by a relatively thick portion of the base below said wire seats.

2. An insulator comprising a base and a cap, the cap having a regularly conical active surface extending substantially to its lower end and the base having a central seat for the cap conforming to but of substantially less depth than said surface whereby when the cap is in said seat the upper portion of its active surface is above said seat, the base also having an annular wire seating shoulder circumscribing said seat at the upper edge thereof and extending at a slight upward inclination from said upper edge, and having wire centering flanges upright from said shoulder at opposite sides thereof with recesses between the terminals of said flanges through which the wires are led, the upper portion of the active surface of said cap overhanging said shoulder whereby said shoulder and said cap provide wire-receiving mouths in which the wires are laterally bent and exert wedging pressure on the laterally bent portions of the wires.

In testimony whereof I have hereunto set my hand in presence of two subscribing wit nesses.

JOHN E. MAIR. Witnesses:

R. L. ENGLISH, HARRY C. CORNELL.

Copies of this patent may be obtained for five cents each, by addressing the Gommissioner of Patents, Washington, D. C. 

